H3C S7500 Series Ethernet Switches Operation Manual

Operation Manual – VLAN
H3C S7500 Series Ethernet Switches Chapter 1
VLAN Overview
1-6
Table 1-3 Packet processing of a Hybrid port
Processing of an incoming packet
If the packet does not
carry a VLAN tag
If the packet carries a
VLAN tag
Processing of an
outgoing packet
z If the port is already
added to its default
VLAN, add the
default VLAN tag to
the packet and then
forward the packet.
z If the port is not
added to its default
VLAN, discard the
packet.
z If the VLAN ID is one of
the VLAN IDs allowed
to pass through the
port, receive the
packet.
z If the VLAN ID is not
one of the VLAN IDs
allowed to pass through
the port, discard the
packet.
Send the packet if the
VLAN ID is allowed to pass
through the port. Use the
port hybrid vlan
command to configure
whether the port keeps or
strips the tags when
sending packets of a VLAN
(including the default
VLAN).
1.3 Protocol-Based VLAN
1.3.1 Introduction to Protocol-Based VLAN
Protocol-based VLAN is also known as protocol VLAN, which is another way to classify
VLANs besides port-based VLAN. Through the protocol-based VLANs, the switch can
analyze the received un-VLAN-tagged packets on the port and match the packets with
the user-defined protocol template automatically according to different encapsulation
formats and the values of specific fields. If a packet is matched, the switch will add a
corresponding VLAN tag to it automatically. Thus, the data of the specific protocol is
assigned automatically to the corresponding VLAN for transmission.
This feature is used for binding the ToS provided in the network to VLAN to facilitate
management and maintenance.
1.3.2 Encapsulation Format of Ethernet Data
This section introduces the common encapsulation formats of Ethernet data for you to
understand well the procedure for the switch to identify the packet protocols.
I. Ethernet II and 802.2/802.3 encapsulation
In the link layer, there are two main packet encapsulation types: Ethernet II and
802.2/802.3, whose encapsulation formats are described in the following figures.
Ethernet II packet:
DA&SA(12) Type(2) Data
Figure 1-4 Ethernet II encapsulation format
802.2/802.3 packet: